| |
Presented at the NABS Annual meeting, Pittsburgh, Pennsylvania, 2002
in Hyporheic Processes
MICROBIAL PRODUCTION IN THE HYPORHEIC ZONE OF A COASTAL FLOODPLAIN RIVER.
S.M. Clinton1 and R.T. Edwards2. 1Center for Streamside Studies, University of Washington, Seattle, Washington, USA 98195, 2Pacific Northwest Research Station, USDA Forest Service, 2270 Sherwood Lane Suite 2A, Juneau, Alaska, USA 99801-8545
Availability of labile dissolved organic matter (DOM) often limits microbial metabolism in river ecosystems. In floodplain rivers, long hyporheic flowpaths occur beneath productive riparian terraces whose soils may be a source of labile DOM. We investigated how variation in microbial production related to differences among riparian soils of varying forest successional stages and position along flowpaths in the hyporheic zone of a floodplain terrace on the Queets River, WA, USA. Samples for microbial production were collected seasonally (4 times) from 30 wells during 2000-2001 and assayed using the 3H-leucine technique. Microbial production was higher at the head of flowpaths than at the flowpaths ends; however it did not decrease in a fashion predicted from other studies. Although microbial production was higher in wells overlain by older forest patches, production was not statistically related to the overlying patch structure. These inconsistent patterns of microbial production along flowpaths and among successional patches demonstrate that neither advecting surface water nor riparian soil inputs solely determines rates of microbial activity in the Queets River floodplain hyporheic zone. Instead, subsurface production reflects a mixing of DOM sources that result in a heterogeneous pattern of microbial activities.
|
|
